Technical Abstract:
The objective of this study was to quantify the genetic diversity among the breeds under evaluation at the USDA, ARS, Subtropical Agricultural Research Station (STARS). Twenty-six microsatellite loci were used to estimate parameters of genetic diversity among a Bos indicus breed, Brahman (B), and three Bos taurus breeds, Angus (A), Senepol (S), and Romosinuano (comprised dof two distinct bloodlines, R1 from Colombia and R2 from Costa Rica). Forty-seven animals from each of the respective STARS herds were selected by pedigree and sampled as breed or bloodline representatives. Analysis was performed using GENEPOP v3.2a. The genetic differentiation detected between the populations was highly significant (P < 0.001). Pairwise measures related to genetic differentiation are shown (Table 1). The R1 and R2 populations were most similar, having the smallest genetic distance (DS; 0.349), population subdivision (FST; 0.143), and proportion of private ealleles (Pvt alleles; 0.106), and the largest gene flow (NM; 0.485). The and R1 populations appeared to be most diverse, having the largest FST (0.309) and proportion of Pvt alleles (0.184), and the smallest NM (0.190). Results indicate that the use of molecular genetic techniques combined with population genetics analyses may be useful to substantiate historical development of these breeds. In conclusion, inferences based on genetic distance were shown to be useful in purebred studies, and may be used to determine relationships between breed diversity and observed heterosis in future crossbreeding studies.